How to monitor if portal access through browser is down

Question

I would like to catch the alert before users report Web site not
accessible(HTTP 404). I'm thinking of an unix cron job. But what
should I querry to check the status of Portal?

Answer 1

In case you are still looking for responses to your question --
We've been using a product called "WhatsUp Gold" from Ipswitch
Inc. (http://www.ipswitch.com/products/whatsup/) to do
monitoring like this for the past few weeks, and so far it's
worked very well. I put a few simple "monitoring" pages on our
web servers to return the status of each of the services, then
we poll these pages every 60 seconds. If we don't get the
expected response back from any of these queries, WhatsUp sends
out emails and pages telling us what machine and what service is
down.
So far I'm polling the basic HTML service, the database
connection (mod_plsql), the servlet service, JSP, and am working
on a way to poll our report server engines and cluster
machines. (I took the "poll exactly one and only one service at
a time" approach so whenever something crashes (usually no more
than once or twice a day... <sigh>), I know exactly what piece
went down.)
- Bill